FAQ

Get more in-depth answers from questions previously asked by our customers and partners.

Category

Acoustics

Why is the acoustic properties of an environment important?

Noise is audible energy that can adversely affect ones physiological and psychological wellbeing. The use of sound absorbing material reduces sound reflection and will create a comfortable indoor climate.

Stone Wool Acoustic Tiles

Stone wool is by nature a highly sound absorbent material, bringing excellent acoustic properties to our ceiling and wall solutions. This allows you to achieve a high level of acoustic comfort while maintaining a high level of aesthetics. The acoustical ratings of Rockfon products have been tested in independent and certified laboratories.

In schools, up to 70% of the consonants spoken by teachers cannot be heard by pupils(1)

In hospital environments, noise control is very important to the recovery of patients as “unwanted sound” can increase heart rate, blood pressure and respiration rate(2)

In offices, 70% of employees believe that their productivity would be higher if their environment was less noisy(3)

When a sound wave hits a surface, part of the energy is reflected, the material absorbs part of it and the rest is transmitted. The quality of sound absorption is determined by the layout of the space and the materials used.

By nature, stone wool offers excellent sound absorption properties.

Proper sound absorption

Sound absorption controls the ambient sound pressure level in a room to create comfortable environments in which people can concentrate and work productively without noise-induced irritation or stress.

It increases speech intelligibility making presentation and conversation easier to understand.

It reduces reverberation (echoes) and the ‘cocktail party’ effect where sound levels rise uncontrolled in a room as people talk louder and louder to make themselves heard until everyone is shouting.

How much sound travels from one room to another?

Our stone wool ceilings can help limit the transmission of unwanted sound from one room to another. The total sound insulation of adjacent spaces is expressed by DnT,w, R´w or DnT,A values. It represents the ability of a total construction (partition, ceiling, floor and all connections) to block speech, music or other noise, that is transmitted through the air and through building elements. The higher the value (in dB) the better the performance.

Some regulators prescribe minimum levels of 35-45 dB between offices or 50-60 dB between apartments and dwellings. Mass, air-tightness and absorbing ability are the primary properties that determine the ability of a material to insulate sound. Mass, air-tightness and sound absorption are the primary properties that determine the ability of a material to insulate against sound.

The impact sound insulation between two floors is an expression of the ability of a construction to insulate from sounds generated by impacts e.g. footsteps, slamming doors. It is characterised by the impact sound pressure level L’nT,w and is rated in dB. The lower the value the lower the sound pressure level thus the better the impact sound insulation. Some regulators prescribe maximum L’nT,w (L’nT(Tmf,max),w in the case of schools) levels of 60 dB in classrooms and offices.

Sound transmission paths between adjacent spaces

Rockfon stone wool ceilings can help limit the transmission of sounds from one room to another.

Improved sound insulation

All walls and ceilings, to some degree, limit sound transmission from one room to another.

The use of building elements with superior sound insulation properties contributes to a higher degree of privacy and confidentiality.

Sound pressure level indicates how loud it is in the room. Exposure to continual high sound pressure levels or to high sound peaks can, over time, damage an individual’s health.

Average sound pressure level is important for all environments – from factories to kindergartens. The European Union has defined maximum exposure levels at 85 dB(A), and in some countries, public events like concerts should not exceed 96 dB(A).

The sound pressure level in a room depends on the strength of the sound source, the room shape and the number and quality of sound absorbing surfaces.

Source: United States Department of Labor, Occupational Safety and Health Administration

Industrial environments very often have high sound pressure levels and require specific acoustic corrections. Rockfon offers a selection of solutions like high absorbing ceilings, baffles or wall absorbers.Sound pressure level indicates how loud it is in the room. Exposure to continual high sound pressure levels or to high sound peaks can, over time, damage an individual’s health.Sound pressure level indicates how loud it is in the room. Exposure to continual high sound pressure levels or to high sound peaks can, over time, damage an individual’s health.

What is the reverberation time an indication of?

The most important factor in all regulations is reverberation time, which is defined as the time it takes for the sound pressure level to drop 60 dB below its original level.

In most cases, a low reverberation time improves the acoustical comfort. In some situations, however, such as concerts or conference halls, a higher reverberation time can improve listening comfort.

Reverberation time depends on the size and shape of the space along with the amount, quality and positioning of absorbing surfaces within the space. The more sound absorption in the room, the lower the reverberation time.

What does speech intelligibility indicate?

Speech intelligibility measures how well speech can be heard and understood in a room. It is closely linked to reverberation time.

Many factors influence speech intelligibility. These include the strength of the speech signal, the direction of the source sound, the level of background noise, the reverberation time of the room and the shape of the room.

The common way of expressing speech intelligibility is the Speech Transmission Index (STI) value on a scale from 0 to 1. In a class room, for example, the level should preferably be above 0.6. A simplified (faster) tool for speech intelligibility is the Rapid Speech Intelligibility Transmission Index (RASTI).

What is sound insulation?

Total sound insulation is the ability of a room (partitions, ceiling, floor and all connections) to prevent sound from travelling through the air and through building elements.

The total sound insulation of adjacent spaces is expressed by DnT,w, R’w or DnT,A values. The higher the value (in dB), the better the performance. Mass, air-tightness and absorbing ability are the primary properties that determine the ability of a material to insulate against sound. Some regulators require a minimum of 35-45 dB between offices.

Experience by the user:

30 dB (A)A conversation in the adjacent room can be clearly heard and understood

40 dB (A)A conversation in the adjacent room is experienced vaguely

50 dB (A)The sound in the adjacent room cannot be heard

Impact sound insulation

Impact sound insulation between floors is the ability of a construction to insulate from impact noises such as footsteps. It is characterised by the impact sound pressure level L’nT,w in dB. The lower the value, the better the impact sound insulation. Regulators usually allow a maximum L’nT,w of 60 dB in classrooms and offices.

What are the main indicators for sound absorption?

Sound absorption is measured using the sound absorption coefficient alpha (α), which has a value between 0 and 1.00. Zero represents no absorption (total reflection), and 1.00 represents total absorption of the incident sound. This coefficient is used to determine the commonly used sound absorption indicators explained below:

Weighted sound absorption coefficient (αw)

Alpha W or αw is calculated in accordance with ISO 11654 using the practical sound absorption coefficient αp values at standard frequencies and comparing them with a reference curve. All suspended ceiling suppliers in Europe provide αw for their products.

Stone wool used in Rockfon products offers the highest performances compared to many other materials.

Equivalent sound absorption area (Aeq)

The sound absorption property of islands and baffles is quantified using the equivalent sound absorption area Aeq expressed as m² per object. The Aeq value is measured in accordance with the ISO 354. This is the area of a fictive absorbing surface of αw = 1.00 which would absorb the same amount of sound as the tested island or baffle. There is no standardised “weighted” equivalent sound absorption area, so the best way to compare a plane ceiling with a ceiling of islands or baffles is to calculate the reverberation time for each room and situation.

Rockfon islands and baffles provide high sound absorption where modular suspended ceilings are not suitable.

Absorption classes

The international standard ISO 11654 breaks absorption performance into five classes, from A to E. The αp values are compared to a series of fixed reference curves. The range between the reference curves is wide, so absorption classes provide only a rough indicator of sound absorption.

Many Rockfon ceilings offer class A sound absorption.

Noise Reduction Coefficient (NRC)

Calculated in accordance with ASTM C423, the Noise Reduction Coefficient (NRC) provides a single-number rating for sound absorption (higher values are better). It is the mathematical average of the measured sound absorption coefficient αs at 250, 500, 1000 and 2000 Hz frequencies. NRC gives equal weighting across the frequency range, which means it is not as accurate as αw.

What are the main indicators for sound insulation?

Room-to-room sound insulation

The Dn,f,w value in dB quantifies the longitudinal sound insulation provided by the ceiling between two rooms. The higher the Dn,f,w value, the better the room-to-room sound insulation. The Dn,f,w value can be considered equal to the previously-used Dn,c,w value.

Dn,f,w is used by acousticians to predict the total sound insulation DnT,w (R’w; DnT,A) between adjacent spaces.

Direct sound insulation

The direct sound insulation in dB indicated by the sound reduction index (Rw) measures the reduction of sound passing through the suspended ceiling.

Ceilings with high sound reduction index Rw will help prevent noise generated by installations in the plenum from entering the room.

C & Ctr values

To rate the impact of sound insulation in specific conditions, laboratories report Dn,f,w or Rw indicating C and Ctr values. C is the adaptation term for “pink” noise such as speech, music, TV, children playing, etc. Ctr is the adaptation term for traffic noise. The lower the C and Ctr values, the better.

How does sound absorption influence on room-to-room sound insulation?

There is a strong synergy between sound absorption and the room-to-room sound insulation experienced in practice. This is not reflected by the Dn,f,w value measured in laboratories. At equal Dn,f,w value, the use of a highly sound-absorbent ceiling will result in a lower sound pressure level in the receiving room.

The ceiling with the highest αw will do a better job of lowering the sound pressure in both the sending and the receiving room. The impact of sound absorption on the perceived sound pressure level can be calculated and has been verified through in-situ testing.

With an identical Dn,f,w value (in this case 44 dB), a high-absorbing ceiling contributes to a lower sound pressure level than a low-absorbing ceiling.

The Rockfon dB range

Our dB range has been designed to block sound from travelling from room to room, providing a unique combination of both outstanding sound insulation and sound absorption in one panel.

Fire

How does stone wool prevent the development or spread of fire?

Stone wool is the safe basis of all Rockfon products. It is made from basalt rock which is by nature noncombustible.

Rockfon has invested heavily in fire testing and related developments.

Behaviour of different materials according to the standard time/temperature curve of Fire resistance standard ISO 834. To contribute to the prevention of the devastating effects of fires, two European regulations apply to construction materials:

Indoor climate

Although we cannot control the quality of the outside air or ventilation, we can ensure that our products contribute positively to the indoor climate regardless of where they are installed.

All our products fulfill E1 classification, guaranteeing that they exceed European Union requirements for formaldehyde emission.

The strict Finnish Indoor Climate label, M1 and the Indoor Climate Label have been attributed to a representative panel of our products, showing that they go beyond legal requirements for emissions in indoor environments.

We do not use photocatalysts, as scientific studies have found they can contribute to secondary emissions that are detrimental to human health. (WHO 1989, Wolkoff et al 1997).

Why is light reflection important for indoor climate?

Poor lighting can result in eye strain, fatigue and aching which in turn is likely to lead to deterioration in performance, particularly if work relies on visual equipment such as computer-based job roles. As this type of work is now common place, the importance of lighting for visual health and performance at work is likely to become increasingly important. Light is important to our wellbeing and performance.

The quality of modern artificial light has improved, but the most comfortable and economical light still comes from the sun, although not sufficient and often combined with artificial light. As a result, not only the amount of light, but also the quality of light is important. Both need to be adapted to the working circumstances in a room. The light reflecting capacity of a ceiling will not only contribute to a reduction in electricity bills but will also improve the quality of lighting conditions. Next to sunlight and artificial light we can make a distinction between direct and indirect light. Direct light will light directly, whereas indirect light is the result of light reflection. As the ceiling is the only surface in a room that is completely visible, the light reflection should be as high as possible to make effective use of the light.

A ceiling with the right combination of high light reflection and a good spread of light (light diffusion) leads to a uniform and accurate spread of light in a room, leading to a reduced need for light fixtures.

Thermal insulation properties of ceiling tiles

Better insulation of buildings is a profitable way to reduce the CO2 emissions; it is a low hanging fruit in combatting climate change. Insulation reduces today’s unnecessary waste of fossil fuels from buildings which are responsible for 40% of the EU and US energy consumption and a major contributor to man-made CO2 emissions. The developing countries - struggling with energy poverty and air pollution – also has a need for buildings that waste less energy and emit less CO2.

Although we are primarily designed for acoustic solutions, there are also situations where the benefit of the intrinsic thermal insulation capacity of ROCKWOOL base material, as a major component of Rockfon ceiling tiles, can be used efficiently.

This is the case when shopping malls build over parking garages as well as in flat-roof buildings or in old buildings with cold cellars. The Rockfon ceiling needs to be seen as part of the total thermal insulation solution taking into account building physics (e.g. condensation, avoiding thermal bridges, etc). We provide products specially designed for thermal insulation in combination with acoustic absorption.

Humidity and sag resistance

How dimensionally stable are Rockfon products under humid conditions?

In buildings under construction which are not yet hermetically sealed or where materials have not dried out, moisture problems can occur. Additionally, in wet rooms such as swimming pools, kitchens and sanitary areas, humidity levels can be exceptionally high.

Humidity can weaken the structure of certain ceiling materials and cause them to sag. In extreme cases, they may even fall out of the grid. Equally, corrosion of metal parts can provide a hazard that should be avoided by installing suspended ceilings with enhanced corrosion resistant (ECR) grids.

Rockfon ceiling tiles are dimensionally stable at up to 100% relative humidity and can be installed at temperatures ranging from 0°C to 40°C. No acclimatization period is necessary, and Rockfon ceiling panels can be installed in the early stages of construction (when the windows are not fully sealed) without any risk of distortion.

Their lightweight, yet stable non-hygroscopic character, minimizes the final weight of the fully-installed ceiling that also reduces the number of hangers needed for their installation. In accordance with EN 13964 our Chicago Metallic™ grid assortment is classified in four classes of grids,- A,B, C, and D- with B being the standard in regular conditions such as office, retail and schools. For environments with a high relative humidity (>90%) and high risk of condensation, Class D grids should be installed with Enhanced Corrosion Resistance.

Cleaning and hygiene

All our ceilings can be cleaned with a vacuum cleaner fitted with a soft brush attachment.

Selected ceilings, like Rockfon Blanka, with a micro-textured surface can be cleaned using a damp cloth or sponge.

Rockfon MediCare Plus and Rockfon MediCare Air products have a durable, highly water-repellent surface that resists diluted solutions of ammonia, chlorine, quaternary ammonium and hydrogen peroxide. They can also be disinfected twice a year using steam cleaning following a protocol defined by experts and using an adapted surface mop.

For more information on the cleaning properties of our products, please refer to product section.

Does stone wool provide sustenance for micro-organisms?

Our ceiling tiles are made of water-repellent stone wool. Stone wool provides no sustenance to the following microorganisms (tested in accordance with JIS Z 2801:2000, ASTM C 1338-96 and NFS 90-351:2013:

Escherichia coli

Staphylococcus aureus

Methicillinresistent staphylococcus aureus (MRSA)

Stachybotrys chartarum

Penicillium brevicumpactum

Alternaria tenuissima

Aspergillus Brasiliensis

Sporobolomyces roseum

Rhodotorula rubra

The Rockfon MediCare range offers four levels of hygienic performance (Rockfon MediCare Standard, Rockfon MediCare Plus, Rockfon MediCare Air and Rockfon MediCare Block) designed to meet the requirements of zones with different levels of infection risks in healthcare facilities.

Impact resistance

Do Rockfon tiles and panels withstand mechanical impact?

Along with sound absorption, the impact resistance of construction materials is an important issue in schools and gyms. Ceilings in these kinds of areas need to be able to withstand tougher-than-average wear and tear as well as frequent demounting.

The impact resistance of suspended ceilings is tested according to EN 13964:2014 annex D and evaluates the total ceiling system (tiles and all grid components). It defines three impact resistance classes:

Class 1A ceilings should be installed in any sports hall where heavy-impact ball sports are played.

Class 2A ceilings can be installed in sports centres where low-impact ball sports are played and in heavy-duty school areas.

Class 3A ceilings can be installed in rooms where the ceiling must fulfil basic requirements on impact resistance e.g. classrooms, school corridors.

The test procedure for impact resistance indicates the ability of a ceiling to resist the incidental impact of balls under normal conditions in sports halls.

Sustainability

Rockfon and sustainability?

As part of the ROCKWOOL Group’s portfolio, the core of everything we do is linked in our purpose to release the natural power of stone to enrich modern living.

Our products help our customers and their communities to tackle the challenges of modern life, by providing comfort, safety and resource efficiency. Stone is the core, raw material we use to produce our stone wool and it is the bedrock on which we have founded our business.

We continuously strive to support your sustainability ambitions regardless if you are looking to certify your whole building according to a sustainability scheme or focusing more narrowly on, among other things, on circularity, low emissions, indoor climate or responsible sourcing.

We transparently document and communicate the sustainable profile of our products using our Product Sustainability Declarations, designed around the major sustainability building schemes and our EPDs.

CE marking

What product properties do Rockfon declare in terms of CE marking?

Customers need to be able to trust the declared performance of ceiling manufacturers and that is exactly the purpose of CE marking. The European Committee for Standardisation (CEN) introduced the EN 13964 norm for suspended ceilings which has been mandatory since 1st July 2007.

The norm aims to make it easier to compare suspended ceilings. To achieve this, it defines those product characteristics which can or must be declared on product labels and in product documentation. In the interest of maximising the information we provide to our customers, we have selected a considerable number of parameters that are now declared for each of our CE marked products. We not only declares the mandatory properties Reaction to Fire and Emission of Formaldehyde, but also sound Absorption, flexural tensile strength, durability, thermal insulation, as well as informing customers on values for light reflection, impact resistance and sound insulation when relevant.

All of our relevant ceiling tiles have been CE marked since October 2005, across all our factories in Europe. In addition, we have chosen the highest level of attestation ofconformity AVCP1. This means that an independent certification organisation – Belgian Construction Certification Association (BCCA) – has verified our initial type testing program and continuously retains our product documentation and production facilities under surveillance. All declared AVCP1 and 3 values have been tested and verified by independent and accredited laboratories. Furthermore, our continuously audited Factory Production Control will always ensure that customers receive products that live up to the standards of the product performance declared under the CE mark.